A gear is cylindrical shaped wheel that is used for transmission of reciprocate or rotational motion from one part of the machine to the other. When there is one or more gears, the connection between them allow flow of power from one shaft or axle to the other. The parallel shaft gears are used for transferring power of rotational motion between the parallel shafts. They offer maximum horsepower for long - term efficiency. It is also effective in carrying high load and it does not make too much noise while being operated. However, producing these types of gears are expensive and it also creates axial thrust. They are used for machines with manual transmission like car steering.
There are many types of gears in the market and they are manufactured according to the type of material, shaft, size, purpose and many other things. Different criteria are used for classification of gears. The most common way of categorizing them is with the arrangement of shafts. So gears and shafts are used combined. There are three types of arrangement of shafts -parallel shafts, intersection of shafts, non- intersecting or non-parallel axis. The intersecting shaft gears allow smooth transfer of power and motion between the axes that are perpendicular to each other. The gears that fall in this category are bevel, angular and crown gear. These are generally used in locomotives and marine applications.
The non-intersecting gears and shafts are used in applications that need high - ratio speed and that can provide power transmission within a specific area with gears and non-intersecting axes. This is the most inexpensive gear as its cost of production is low and it has a limited capability to carry load. This problem can be easily resolved by lowering the ratio for increasing efficiency. The non-intersecting shaft gears are worm hypoid and cross- helical and are generally seen in passenger lifts, electric mixers and heavy vehicles. Many systems categorize use of gears according to the diameter, material, design, number of steps and many other things. The aim of this system is providing adequate information to the consumers for their needs.